The indicator is created by the book of Larry Williams "Long-term secrets to short-term trading". But instead of identifying a trend by reversal points, there is added the trend Moving Average located on the zero line to define the direction of deals. For clarity the indicator is replaced to a separate window and the price is normalized by the trend MA. The meaning is in the following:
Translated from Russian by MetaQuotes Software Corp.
Original code: https://www.mql5.com/ru/code/1111
The Acceleration/Deceleration Indicator (AC) measures acceleration and deceleration of the current driving force.Average Directional Movement Index (ADX)
The Average Directional Movement Index Indicator (ADX) helps to determine if there is a price trend.